1. Field of the Invention
The present invention relates to a control circuit for holding constant the operating voltage of an electronic load that can be operated at different line voltages, with an electronic switch that is controlled by the phase angle and that is connected in series with the load.
2. Description of the Prior Art
It is known that electronic loads, especially small electric appliances, can be connected to different line voltages in the range of, for example, 100 to 240 volts AC, by using a so-called phase-angle control, without the electric loads being adjusted for the particular line voltage by a corresponding switchover mechanism.
Phase-angle controls as such have also been used to control the brightness of electric incandescent lamps. In such a case, a time constant or a phase bridge for the time shift of the ignition voltage of a phase-angle controllable electronic switch is changed by means of a variable resistor. Transistors, thyristors, or triacs are generally used as the phase-angle controllable switch.